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Medicine 1 (Year 1) > Physiology - Respiratory > Flashcards

Physiology - Respiratory Flashcards

1
Q

The function of the respiratory system

A
  1. Gas exchange (02 added to blood from air. C02 removed from blood to air) 2. Acid base balance - pH 3. Protect from infection 4. Communicating via speech
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2
Q

Why do we need to breathe? Why is gas exchange so important

A

To produce energy

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3
Q

Energy is

A

Fundamental in all living systems

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4
Q

What does 02 relate to energy in living systems

A

Burning oxygen produce carbon dioxide Respiratory system responsible for 02 in and c02 out

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5
Q

What 2 systems does gas exchange link?

A

Respiratory system and cardiovascular system

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6
Q

What biochemical process releases energy from glucose either via glycolysis or oxidative phosphorylation.

A

Cellular/internal respiration

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7
Q

What is cellular/internal respiration?

A

biochemical process releases energy from glucose either via glycolysis or oxidative phosphorylation.

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8
Q

What is the movement of gases between air and body cells via both resp and CVS

A

External respiration

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9
Q

What is external respiration

A

the movement of gases between air and body cells via both resp and cvs

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10
Q

Which produces more energy (ATP) Glycolysis or oxidative phosphorylation

A

oxidative phosphorylation

we cannot survive on glycolysis alone

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11
Q

explain the pulmonary circulation compared to systemic circulation

A

pulmonary circulation is opposite systemic circulation in function and terminology

Pulmonary circulation delivers Co2 to lunch and collects 02 from lungs.

Systemic circulation delivers 02 to peripheral tissue and collects co2

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12
Q

Pulmonary circulation _______ (delivers/collects o2 co2)

A

Pulmonary circulation delivers Co2 to lung and collects 02 from the lungs.

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13
Q

Systemic circulation ________ (delivers/collects o2 co2)

A

Systemic circulation delivers 02 to peripheral tissue and collects co2

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14
Q

Pulmonary ___ carries ____ blood

Pulmonary ___ carries ___ blood

A

Pulmonary arteries carry deoxygenated blood

Pulmonary veins carry oxygenated blood

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15
Q

upper respiratory system

A

Nose - enters the body through the nose (more effective than the mouth) where cilia and mucus trap and warm moisten the air.

Pharynx - from nose air moves down the pharynx or throat, which is shared with the digestive system

Epiglottis - this small flap of tissue folds over the trachea and prevents food from entering it when you swallow.

Larynx - the voice box, contains vocal chords that vibrate to produce sounds

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16
Q

Lower respiratory tract system

A

Trachea - from the pharynx air moves down toward the lungs through the trachea. made up of stiff rings of cartilage that support and protect it. travels down to sternal angle (splits for 2 primary bronchi)

Bronchus - Air moves from the trachea into the right and left bronchi, which lead inside the lungs

Lung - The main organs of respiration - soft, spongey texture is due to the many thousands of tiny hollow sacs that compose them

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17
Q

where does gas exchange occur?

A

Alveoli (little sacs in lunchs)

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18
Q

How many fissures in the right lung?

A

two fissures in the right lung split the lung into three lobes.

horizontal fissure and oblique fissure.

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19
Q

which fissure splits the superior lobe from the middle lobe

A

horizontal fissure

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20
Q

the horizontal fissure splits which lobes?

A

superior lobe of the right lung to the middle lobe.

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21
Q

the oblique fissures split

A

Right lung - middle lobe from inferior lobe

left lung - superior lobe and inferior lobe

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22
Q

which fissure splits superior and inferior lobes and which lung

A

Left lung - oblique

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23
Q

how many fissured on left lung?

A

one - oblique fissure

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24
Q

What cavity is inside the thoracic cavity?

A

The pleural cavity

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25
Q

Define the thoracic cavity

A

Defined by the ribs within the inferior border being the diaphragm and pleural cavity is a cavity within the thoracic cavity.

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26
Q

The trachea branches at what level?

A

Sternal angle

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27
Q

each bronchus branches __ times

A

22 times

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28
Q

Bronchopulmonary segments

A

as well as lobes lung tissues are broken into tertiary segments and one tertiary bronchi going to each segment of the lung

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29
Q

the semi ridgid tubed of the airway are maintained by

A

c shaped rings of cartilage

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30
Q

why do the upper airways, trachea and bronchi have c shaped rings of cartilage

A

to maintain patency of airway - give degree of rigidity that stops them collapsing or getting compressed.

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31
Q

how many of generations of branchine between the trachea and alveoli

A

24 generations

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32
Q

where do the cartilaginous rings stop down the airway?

A

beyond the bronchi - into bronchioles and smaller

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33
Q

what holds the airways open if the cartilaginous rings are not present

A

patency is maintained by the physical forces that act on the lungs.

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34
Q

where is dead space - how much dead space is there.

A

bronchi, bronchioles, and trachea as they are too thick-walled for gas exchanged. There is roughly 150 milliliters of air sitting in dead space

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35
Q

which bronchi are wider and more verticle - why is this significant?

A

The right bronchi is wider and more vertical - aspirated foreign bodies are more likely to get stuck in the right bronchi

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36
Q

where is the most air resistance to the airflow?

why?

A

from the trachea to smaller bronchi

The cross-sectional area is larger in bronchioles and alveoli (because they have more divisions all around - each small air way has many generations and openings where trachea e.g. has only one large opening)

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37
Q

what does bronchodilation do to resistance in lungs

A

dilates the airways - lowers resistance.

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38
Q

where is the “conduction zone?”

A

Trachea

primary bronchi

smaller bronchi

bronchioles

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39
Q

Where is the respiratory zone

A

alveoli

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40
Q

what does air in the conducting zone do?

A

Sits in “dead space”

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41
Q

airway diameter and resistance can be altered by

A

the activity of bronchial smooth muscle

contraction decreases diameter = increases resistance

relaxation increases diameter = decreases resistance

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42
Q

sympathetic acts on bronchial smooth muscle

which receptors

A

the sympathetic nervous system acts on beta two receptors (two lungs) cause bronchial smooth muscle relaxation.

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43
Q

sympathetic acts on bronchial smooth muscle what happens, what transmitters on what receptor

A

when adrenaline and noradrenaline bind to beta two receptors in the lungs it causes relaxation smooth muscle then increases the diameter of airway = reduces resistance

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44
Q

In sympathetic response, why do re want this reaction to our lungs?

A

increase dilation and reduced resistance means more ventilation

increased 02 delivery to our muscles means more energy so they can function more efficiently so we can fight or flight (run)

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45
Q

airway to the alveoli - gas exchange to which system

A

this is where exchange can take place in direct contact with tthe only part of the cardiovascular system. (cardiovascular tree)

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46
Q

what CVS bed is surrounding the area of gas exchange in respiratory system

A

capillary bed (network of capillaries) are surrounding the alveoli

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47
Q

what does the CVS bed (attached to the area of gas exchange in respiratory) then join on to, to continue the CVS circulation

A

Pulmonary artery - which carries deoxygenated blood back from the systemic venous circulation coming from the right side of the heart to the lungs.

carrying blood full of co2

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48
Q

Once the blood is oxygenated in the cvs bed surrounding the alveoli ____

through the ______

A

flows out of the capillary bed to the left side of the heart through the pulmonary vein

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49
Q

what are elastic fibres for that surround alveoli

A

they expand during inspiration and released expiration to squeeze alveoli and force air out of the respiratory system. (expiration at rest is passive)

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50
Q

expiration at rest is__

A

passive

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51
Q

alveoli components

A

one type of cell makes a bulk alveolar wall.

studded with type 2 cells which release surfactent

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52
Q

which type of cells do gas exchange and which do not

A

type1 cell makes a bulk alveolar wall - gas exchange

studded with type 2 cells which release surfactant NOT FOR gas exchange

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53
Q

which alveoli cell does not do gas exchange, what does it release.

A

studded with type 2 cells which release surfactent

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54
Q

which WBC are around the respiratory system

A

macrophages - important for immunity

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55
Q

why are there WBC dotted on the respiratory system?

A

The respiratory system is one of the points in the body where the external environment and internal environment meet. - important to have lots of immune tissue

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56
Q

emphysemia does what to surface area for gas exchange?

A

emphysema results from the destruction of alveoli in a way we lose surface area available for gas exchange

This decrease impacts resp function. Gas exchange between lungs and blood is only possible at alveoli due to thin surface.

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57
Q

Airway resistance determines___

A

how much air flows into the lungs at any given pressure difference between the atmosphere and alveoli.

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58
Q

The major determinant of airway resistance is__

A

the radii of the airways

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59
Q

The surface area of alveoli is ____

how much volume approx?

A

80m2

Fits a volume of approx 6L (3L in each lung)

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60
Q
A
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61
Q

What is ventilation?

A

The bulk flow of air in the lungs and bulk flow of air out of lungs

Does not tell us anything whether that gas or 02 is getting into the blood or co2 can get out of the blood.

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62
Q

What is pulmonary ventilation?

A

total air movement into/ out of the lungs (relatively insignificant in functional terms)

(L/min)

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63
Q

what is alveolar ventilation

A

fresh air getting to the alveoli and therefore available for gas exchange (functionally more significant)

(L/min)

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64
Q

How to tcalculate pulmonary volume?

A

tidal volume x respiration rate?

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65
Q

calculate alveolar difference

A

tidal volume - dead space vol x respiration

= ___(L/min)

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66
Q

Partial pressure

A

Daltol’s Law - total pressure gas micture is sumof pressure of the individual gases.

air = 79% nitrogen and 21% o2. negligible co2 (0.03%)

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67
Q

if patient has ^ c02 is that from breathing too much Co2?

A

no.

it’s due to a pathology which is preventing exhaling out the co2. We are the producers of co2

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68
Q

Define partial pressure

A

The pressure of a gas in a mixture of gases is equivalent to the % of a particular gas in the entire mixture multiplied by the pressure of the whole gaseous mix.

e.g. atmospheric P = 760mmHg

pressure of are we breath therefore = 760mmHg

21% air we breathy = o2

partial pressure of o2 in aie = 21%x760mmHg = 160 mmHg

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69
Q

what is our normal alveolar ventilation?

A

4.2L/min

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70
Q

Why is partial pressure less through alveolar ventilation than calculated?

160,,Hg - in graph 100,,Hg -

A

Air we breathe is diluted by 2 things - anatomical dead space and tidal volume breathed in are only 70% efficient and the air is diluted (saturates) with water vapour.

and pressure of gas equilibrium,

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71
Q

what happens with alveolar ventilation during hypoventilation

A

reduction of ventilation due to less air getting to the alveoli for gas exchange

o2 levels in alveoli fail as taken away bu blood + metabolised by peripheral tissue faster than being replenished by alveoli

co2 levels increase faster than able to breathe out = co2 levels rise and seen in blood. > partial pressure of oc2 rise pressure drops of o2 drop

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72
Q

What happens to alveolar ventilation in hyperventilation

A

Increased alveolar ventilation - pressure of o2 rises and oressure of co2 falls

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73
Q

What levels are our primary driving force for breathing?

A

co2 levels

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74
Q

what is alveolar ventilation significantly influenced by?

A

Dead space

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75
Q

which type of ventilation is functionally more important

A

Alveolar ventilation MORE important than pulmonary ventilation

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76
Q

what is more influential in determining alveolar ventilation? rate or depth

A

depth of breathing of more influential than determining alveolar ventilation than the rate of breathing

because of the effect of anatomical deadspace

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77
Q

in what direction does alveolar ventilation decline and why

A

with height from base to the apex of an upright lung due to changes in compliance.

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78
Q

what is normal alveolar partial pressure or 02?

A

normal alveolar partial pressure (asnd therefore systemic arterial PP) of 02 is 100mmHg (13.3 kPa)

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79
Q

what is the normal Alveolar partial pressure of co2?

A

Normal partial prssure ~(and therefore systemic arterial PP) of co2 is 40mmHg (5.3 kPa)

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80
Q

The pulmonary artery carries

A

deoxygenated blood AWAY from the heart to the lungs

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81
Q

The Pulmonary vein carries

A

oxygenated blood TOWARDS the heart from the lungs

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82
Q

Pulmonary circulation ____

A

Is opposite from systemic circulation in the function it delivers co2 to the lungs and picks up o2 from air.

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83
Q

BRONCHIAL CIRCULATION___

A

nutritive supplies via bronchial arteries from systemic circulation to supply oxygenated blood to lung tissues. complises 2%of left heart output. blood drains to left atrium via pulmonary veins

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84
Q

Pulmonary circulation (gas exchange)

A

consists of l+ R pulmonary arteries originating from right ventricles. entire cardiac output from right ventricle. supplies dense capillary network surrounding the alveoli and returns oxygenated blood to the left arrrium via pulmonary vein high flow, low pressure system (25/100mmHg pulmonary vs 120/80mmHg systemic)

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85
Q

systemic artery partial pressure reflects what is happening in ____

A

the alveoli,

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86
Q

systemic venous blood reflects what is happening in

A

our peripheral tissues.

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87
Q

where does systemic venous blood go back to

A

the right side of the heart.

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88
Q

Appreviations

A -

a -

V

A

A - alveolar

a - arterial blood

V - mixed venous blood (e.g. in pulmonary artery)

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89
Q
A
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90
Q

What is Pao2

A

Partial pressure of oxygen in artierial blood

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91
Q

What is PAco2

A

Partial pressure of co2 in alveolar air

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92
Q

with gas exchange, how is the rate of diffusion proportional

A
  • directly proportional to the pressure gradient
  • directly proportional to gas solubility

directly proportional to the available surface area

  • inversely proportional to the thickness of the membrane
  • most rapid over short distances
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93
Q

describe why solubility is important for diffusion rate

A

co2 is very soluble in water o2 is not very soluble the faster it will be if more soluble.

PP o2 100 mmHg - 46mmHg

co2 40mmHm - 46mmHg

so PP would say 02 is faster BUT solubility c02 is more so would be faster - this is why the rate is relatively the same as these 2 factors make the rate similar.

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94
Q

where do the elastic fibres on alveoli never sit

A

between a blood capillary and the alveoli = less distance for diffusion to occur.

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95
Q

diffusion of gases between the alveoli and the blood obey rules of ___

A

simple diffusion

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96
Q

__ diffuses more rapidly because of its ___

however, the overarall rate of ____ between ___ and ___ are similar because of the ______ for ___

A

co2 diffuses more rapidly because of its greater solubility. however, the overall rate of equilibrium between o2 and co2 are similar because of the greater pressure gradient for o2

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97
Q

The anatomy of the lung is optimally adapted to maximise gas exchange because of ___:

A
  • larger surface area, minimum diffusion distance, thin cell membranes (type 1 alveolar cell capillary cell)/
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98
Q

what impact does emphysema have on gas exchange

A

destruction of alveoli reduces surface area for gas exchange

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99
Q

what impact does fibrosis have on gas exchange

A

thickened alveolar membrane slows gas exchange. loss of lung compliance may decrease alveolar ventilation

100
Q

what impact does pulmonary edema have on gas exchange

A

fluid in interstitial space increases diffusion distance

material pco2 may be normal due to higher co2 solubility in water (increase diffusion distance po2 low)

101
Q

what impact does asthma have on gas exchange

A

increased airway resistance decreases airway ventilation

102
Q

in fibrosis what can you see a difference in through histology

A

normal alveoli, blood cells and some connective tissue

in fibrosis presence fibrotic tissue.

103
Q

fibrosis in lung xray

A

fibrosis is opaque you can see

104
Q

emphysema lung

A

emphysema break down the alveolar membrane and loss of elasticity. loss surface areas for gas exchange

105
Q

main cause for emphysema

A

smoking

106
Q

what muscles are people with emphysema having to use for breathing?

A

use muscles of expiration - internal intercostal muscles to pull ribcage down and in

use abdominal muscles to push their abdominal contents up into the diaphragm - push the diaphragm up into thoracic cavity and increase the pressure to force air out.

107
Q

what happens with compliance in fibrosis and emphysema

A

fibrosis - compliance decreases because fibrous tissue resists the stretch.

emphysema - lose elasticity because of breakdown elastic fibres - compliance increases due to lost resistance.

108
Q

what does oedema do to compliance?

A

no effect in compliance - no effect ventilation but increased diffusion distance means harder for gases to (particularly o2) diffuse so impacted partial pressure.

109
Q

what effect foes asthma have on diffusion

A

little effect on diffusion and a mainly big effect on ventilation end up having an impact on the partial pressure of o2 and co2 in alveoli

= reduces pp of 02 and increase pp of co2.

110
Q

emphysema causes ____

A

loss of surface area

111
Q

fibrosis causes _____

A

increased thickness of membrane

112
Q

oedema cauaes___

A

increased diffusion distance

113
Q

what is an obstructive lung disease

A

obstruction of airflow especially on expiration

114
Q

explain restrictive lung diseases

A

restriction of lung expansion

115
Q

Conditions that are obstructive lung diseases

A

Asthma

copd

chronic bronchitis

emphysema

116
Q

Restrictive lung diseases:

A

Restriction of lung expansion + loss of xompliance

Fibrosis

asbestosis

infant respiratory distress syndrome

oedema

pneumothorax

117
Q

what is spirometry

A

the technique used to measure lung function can be static or dynamic

static where only consideration volume exhaled

dynamic time taken to exhale certain vol is what is measured

118
Q

what levels can spirometry measure

A

tidal vol

inspiratory vol

inspiratory capacity

expiratory reserve vol

vital capacity

119
Q

what levels can spirometry NOT measure

A

Total lung capacity

functional residual capacity.

residual volume

120
Q

common lung function tests

A

FEV1/FVC

forces expiratory volume in 1 second

121
Q

what is a normal volume in FEV1

A

fir healthy adult 4.0L

122
Q

what is a normal FVC

A

normal fit health is 5.0L

123
Q

what is normal % of fev1/fvc

A

80%

124
Q

In disease what would fev1, fvc and ratio be in

normal

A

fev1 = 4.0L

fvc = 5.0L

% = 80

125
Q

In disease what would fev1, fvc and ratio be in

obstructive disease

A

fev1= 1.3

fvc = 3.1L

% = 42

126
Q

In disease what would fev1, fvc and ratio be in

restrictive lung disease

A

fev1 = 2.8

fvc = 3.1

% = 90

127
Q

explain fev1 fvc levels in obstructive condition

A

the rate at air exhales is slower

total expired volume (fvc) is reduced (FRC functional residual capacity may be increased)

the major effect is on the airway so fev1 is reduced to a greater extent than FVC

ratio reduced

128
Q

explain fev1 fvc levels in restrictive condition

A
  • absolute rate of airflow reduces (due to total lung vol reduced)
  • total volume reduced due to limitation to lung expansion
  • ratio remains constant or can increase as a large proportion of volume can be exhaled in the first second.
129
Q

obstructive lung diseases increase work of

A

expiration

130
Q

Restrictive lung diseases increase the work of

A

inspiration

131
Q

Distribution of blood flow in lungs

A

Both blood flow and ventilation decrease with height across the lungs

less ventilation and perfusion in the apex of the lung.

132
Q

where is the lung does blood flow or arterial pressure exceeds each other

A

the base of the lungs blood flow exceeds alveolar pressure, this compresses the alveoli.

133
Q

where are the perfusion ventilation mismatches and what are they? where is precisely matched?

A

the apex is mismatched with ventilation exceeding blood flow

the base of the lung is mismatched with blood flow exceeding ventilation

the 3rd rib is where the ventilation-perfusion balance is equal.

134
Q

where is the biggest ventilation-perfusion mismatch?

A

apex

135
Q

what are the ratios of ventilation-perfusion mismatch?

A

perfectly matched ventilationperfusion ratio = 1.0

mismatch 1 (base) = <1.0

mismatch 2 (apex) ventilation > perfusion >1.0

136
Q

what is shunt

A

blood is moved from right side of the heart to the left without gas exchange

137
Q

what happens to blood when it is in an area of the lung that is poorly ventilated? (hypoxia)

A

smooth muscle in the area restrict blood to that area by constricting in response to hypoxia. shunt

perfusion greater than ventilation

alveolar po2 falls = pulmonary constriction

pco2 rises = bronchial dilation

138
Q

what is the systemic circulation response to an area of hypoxia?

A

tissue dilates to allow more o2 to travel to the area

139
Q

what is alveolar dead space?

A

when ventilation exceeds blood flow.

opposite of shunt.

140
Q

what happens (mismatch) with pulmonary embolism?

A

ventilation exceeds blood flow. embolism impedes blood flow = alveolar deadspace.

increase 02 and decrease co2

alveolar po2 rises = pulmonary dilation

pco2 falls - bronchiconstirction

141
Q

What is physiological dead space

A

alveolar dead space + anatomical deadspace

142
Q

Pulmonary arterial pressure is ___ the systolic p ___ diastolic p ___.The ____ pressure circuit susceptible to the effects of ___ and this gives rise to the degree of variability. The ___ of the lung is highly perfused compared with the ___ of the lung

A

Pulmonary arterial pressure is low: systolic p - 25mmHg diastolic p -8mmHg .The low-pressure circuit susceptible to the effects of gravity and this gives rise to the degree of variability. The base of the lung is highly perfused compared with the apex of the lung

143
Q

ventilation varies with ___. and is greatest at the ___. This ventilation is due to changes in the ___ across the lung. The ventilation-perfusion ratio ___ from ___ to__ in the upright lung. This inequality is compensated by ___ of ___ controlled by ___

A

ventilation varies with height. and is greatest at the base. This ventilation is due to changes in the compliance across the lung. The ventilation-perfusion ratio increases from the base to apex in the upright lung. This inequality is compensated by local regulation of blood flow controlled by local po2

144
Q

what describes alveoli that are perfused but underventilated

A

shunt

145
Q

what described alveoli that are ventilated but under perfused

A

alveolar deadspace

146
Q

alveolar deadspace (normally small) + anatomical deadspace

A

physiological deadspace

147
Q

what is respiratory sinus arrhythmia

A

acts to minimise ventilation-perfusion mismatch during the breath cycle.

148
Q

how much is the demand of 02 to resting tissues

A

250 ml/min

149
Q

arterial 02 content (plasma)

A

3ml/L

150
Q

how much 02 can haemoglobin carry?

A

197ml of 02/l

151
Q

how much % of arterial 02 id extracted by peripheral tissues at rest?

A

25%

152
Q

when referring to the partial pressure of oxygen in the blood: what are we referring to

A

we are only referring to the amount of o2 in plasma, NOT referring t how much o2 is wrapped up in haemoglobin

153
Q

the amount of o2 in the solution in plasma is determined by__

A

the partial pressure of o2 that is in our alveoli

154
Q

the partial pressure of o2 in the alveoli is determined by

A

our alveolar pressure

155
Q

what is the normal partial pressure of resting tissues?

how saturated is haemoglobin at this stage?

A

40mmHg

75% saturdates Hb

156
Q

in anaemia describe

A

anaemia is defined as a condition where the o2 carrying capacity of blood is compromised (iron deficiency, haemorrhage, vitb12 deficiency)

157
Q

what would happen to the partial pressure of o2 in anaemia

A

The partial pressure of o2 is normal. total blood o2 is compromised.

the amount of o2 in solution is partial pressure - determined by partial pressure o2 in alveoli.

if normal lung function - normal ventilation - normal diffusion. normal partial pressure o2 in plasma.

LOSS of blood cells or making not enough means no place to store o2

158
Q

can you have a low partial pressure of o2 and normal total blood o2 content?

A

no. because the partial pressure of o2 determines how mich o2 binds to haemoglobin.

if pp falls - o2 content also falls.

159
Q

can you have low o2 content but normal partial pressure of o2?

A

the amount of o2 in solution is partial pressure - determined by partial pressure o2 in alveoli.

if normal lung function - normal ventilation - normal diffusion. normal partial pressure o2 in plasma.

LOSS of blood cells or making not enough means no place to store o2 so low o2 content but normal partial pressure

160
Q

can red blood cells be fully saturated in anaemia?

A

yes can be fully saturated - what determines the saturation of haemoglobin is the partial pressure of o2. (normal) so saturation can occur

161
Q

what factors change affinity of haemoglobin for oxygen?

A

PH

Pco2 (partial pressure co2)

Temp

DPG (diphosphoglycerate) 2,3

162
Q

what happens if there is an increase in factors that determine haemoglobin affinity for 02

(temp, ph, pco2)

A

the affinity for o2 drops releasing more 02

163
Q

what happens if there is an decrease in factors that determine haemoglobin affinity for 02

(temp, ph, pco2)

A

affinity rises and releases less o2.

164
Q

what happens to the affinity of haemoglobin to o2 in hypothermia

A

the affinity is high still, holing on to o2 and not giving to peripheral tissues

165
Q

what is dpg2,3

A

is a by-product of red blood cell metabolism.

166
Q

where or when is dpg 2,3 produced?

A

in situations and regions where there os less o2 available.. in states of hypoxia.

may be in chronic lung disease or chronic heart disease

167
Q

explain carbon monoxide exposure and haemoglobin affinity

A

co binds to haemoglobin 250x more affinity than 02 and slowly dissociates. pc0 of only 0.4mmHg causes progressive carboxyhaemoglibin formation

characterised by hypoxia, anaemia, headache, cherry red sckin and mucous membranes.

resp rate usually unaffected due to normal arterial Pcp2. leads to potential brain damage and death.

treatment involved providing 100% o2 to increase Pao2

168
Q

what is the difference between partial pressure and gas content?

A

arterial partial pressure (Pao2) is not the same as arterial o2 concentrations.

pao2 refers purely to o2 in solution in plasma and determined by o2 solubility and the partial pressure of o2 in the gaseous phase that is driving o2 into solution.

partial pressure is not the same as concentration as varies depending on the form the molecules are in. (e.g. 30x more o2 in 1L gas than 1L in plasma)

169
Q

EXPLAIN air embolism and what this means with gases travelling in plasma

A

gases are travelling around the body NOT in a gaseous phase but in a solution

air embolism is bubbles in the blood where gases are in their gaseous phase travelling in plasma.

170
Q

each litre of systemic arterial blood contains ___ml of o2.

more than __% bound to haemoglobin. the rest is dissolved in ____

Haemoglibin cooperatively binds to __ molecules of o2.

____ml p2 binding to each gram of haemoblibin.

The reaction of o2 binding and releasing from haemoglobin is a ___ reaction not a __ reaction

A

each litre of systemic arterial blood contains -200ml of o2.

more than 98% bound to haemoglobin. the rest is dissolved in plasma

Haemoglobin cooperatively binds to 4 molecules of o2.

1.34ml o2 binding to each gram of haemoglobin.

The reaction of o2 binding and releasing from haemoglobin is an oxygenation reaction not a oxidation reaction

171
Q

name 5 haemoglobin types

A

Haemoglobin A. This is the most common type of haemoglobin found normally in adults.

Haemoglobin F (fetal haemoglobin). This type is normally found in fetuses and newborn

Hemoglobin A2. This is a normal type of haemoglobin found in small amounts in adults.

Glycosylated haemoglobin - HbA1a, HbA1b, and HbA1c is a form of haemoglobin (Hb) that is chemically linked to sugar.

172
Q

what is another oxygen-carrying molecule and where would you usually find it?

when would you find it elsewhere I n the body?

A

Myoglobin

usually found in cardiac and skeletal muscle

you would only usually find in circulation if you have extensive muscle damage

173
Q

explain main types of hypoxia

A

1. hypoxaemic hypoxia - most common - reduces o2 diffusion in lungs due to reduces po2 atmosphere or tissue pathology

2. anaemic hypoxia - reduces o2 carrying capacity due to anaemia, reb loss/ iron deficiency

3. stagnant hypoxia - heard disease inefficient pumping of blood to lungs/around body

4 histotoxic hypoxia - poisoning prevents cells utilising o2 delivered to them e.g. co poisoning/cyanide

5 metabolic hypoxia o2 delivery to tissue doesn’t meet increased demand by cells

174
Q

the partial pressure of the o2 in blood and o2 concentration in the blood is the same things

true or false?

A

false. not the same thing

175
Q

partial pressure describes what in relation to ___

and not ____

A

partial pressure which described amount of o2 in solution in the plasma, not total o2 content in the blood

176
Q

does partial pressure determine o2 content in blood?

A

yes partial pressure determines total o2 content of blood by determining saturation of haemoglobin, where 98% of o2 in blood is carried

177
Q

what has higher affinity HbF or HbA1

A

Haemoglobin HbF (foetal haemoglobin) has a higher affinity for hba1 (adult haemoglobin) to allow them to extract o2 from the maternal systemic circulation that they would otherwise not have access to.

178
Q
A
179
Q

ventilatory Control requires the stimulation of ____ of ___

A

skeletal muscle of inspiration

180
Q

What stimulates the muscles of inspiration?

A

The phrenic nerve (to the diaphragm) and intercostal nerves (to external intercostal muscles)

181
Q

at rest, expiration is _____ so ____ is required

A

at rest, expiration is passive so no neural input is required

182
Q

Ventilatory control what area of spinal cord the origin would breathing cease if severed?

A

breathing dependent on signalling from the brain (sever cord above the origin of the phrenic nerve c3-5 and breathing ceases

183
Q

how is respiratory rhythm modulated by Respiratory centres

A
  1. emotional (via limbic system in the brain) (anxious, crying)
  2. voluntary override (viahigher centres in the brain)
  3. mechano-sensory (stretch receptors) input from the thorax - stretch reflex
  4. Chemical composition of the blood )pco2, po2 and ph) detected by chemoreceptors
184
Q

why do we expire in a smooth controlled manner?

A

use of basal tone in our muscles of expiration. we are not actively causing them to contract - basal tone is slow controlled and smooth. no need to contract we are not forcing air out during expiration at rest

dordal respiratory group switches off and stops inspiratory muscle contraction. relax to starting position

185
Q

where are chemoreceptors for breathing`

A

central and peripheral chemoreceptors

186
Q

explain chemoreceptors for breathing

A

central chemoreceptors: medulla - respond directly to h+ which directly reflects pco2 primary ventilatory drive.

Peripheral chemoreceptors: carotic and aortic bodies

respond primarily to po2 (less pco2) and plasma h+

secondary ventilatory drive

187
Q

central chemoreceptors

A

detect changed in [H+] in csf around brain

causes reflex stimulation of ventilation folliowing rise in [h+] deiven by raised pco2 (hyper capnia)

co2 +h2o h2co3 >-< h+ + hco3-

188
Q

what happens with ventilation with chemoreceptors if there is a decrease in h+

A

ventilation is reflexible inhibited by a decrease in arterial pco1 (reduces csf [h+] = hyperventilation you will stop breathing for a short time because expired all c02

do not respond to direct change in h+

189
Q

why can central chemoreceptors not respond directly to hydrogen ions in plasma

A

they are reflecting levels of co2 in blood the negative feedback loop ensures normal pco2

they cannot respond to hydrogen ions in the plasma because those ions do not cross the blood-brain barrier.

190
Q

what happens with build-up of pco2

A

if we increase pco2 we double ventilation body sensitivity to pco2

191
Q

chronic lung disease explain for ventilation

A

chronically exposed to co2 levels and desensitised.

they rely on peripheral chemoreceptors rely in pao2 - driven by hypoxia.

192
Q

peripheral chemoreceptors

A

carotic artery and aortic body

detect changed in arterial po2 and h+ pao2

cause reflex stimulation of ventilation following significant fall in po2

(below >60mmHg)

  • consider harmoglobin dissosiation curve
193
Q

what will happen to respiration rate in an anaemic patient with normal lung function, who has a blood oxygen content half the normal value?

  1. increase
  2. decrease
  3. stay the same
A

it will stay the same

because lungs are working normally. diffusion take place normal peripheral response to partial pressure o2 and NOT total o2 content. PAO2 NORMAL.

AS PAO2 IS WHAT PERIPHERAL RECEPTOR MONITOR NO INCREASE IN RESP RATE. ASSING MORE O2 WOULD DO LITTLE BECAUSE RBC is already saturated 98%. there are not enough RBC

194
Q

explain sedation/anaesthesia and ventilatory control

A

most gaseous anaesthetic agents increase resp rate but decrease tidal volume (tidal vol is the main determinant of alveolar ventilation)

195
Q

what effect do barbituates/opioids have to respiratory centes?

A

barbiturates and opioids depress resp centres. overdose results in death due to resp failure. decrease in sensitivity to PH and response to pco2. also, decrease peripheral chemoreceptor response reduced po2.

196
Q

explain nitrous oxide to chemoreceptor response

A

a common sedative/light anaesthetic agent blunts peripheral chemoreceptor response to falling pa02. Very safe in most individuals but problematic in chronic lung disease cases where individuals are on hypoxic drive. Administering o2 to these patients aggravates the situation

remember most people work on central chemoreceptors - hypoxic driven work in levels in peripheral chemoreceptors

197
Q

explain why nitrous oxide is not good for patients with chronic lung disease

A

this blunts the peripheral chemoreceptor to pao2 levels dropping. The central chemoreceptors are already lost due to chronic exposure to co2. giving nitrous oxide blunts the peripheral chemoreceptors - patient now has no means of regulating blood gas composition. co2 levels dramatically rise o2 levels drop and the body cannot respond because insensitive - this is dangerous

co2 = toxic - o2 drop cannot supply to the brain - function disrupted.

** giving o2 - co2 is still built up and holds on in the body - the excess 02 stops them from breathing

198
Q

The main factor determining ventilation is

A

the chemical composition of the plasma

199
Q

the strongest factor influencing ventilation is

A

the partial pressure of co2 in the plasma paco2

200
Q

what play a secondary role in ventilation

A

paco2 and plasma ph play a secondary role

201
Q

what play a dominant role in ventilatory control

A

central chemireceptors

202
Q

what play a more minor role in ventilatory control in healthy individuals

A

peripheral chemoreceptors

203
Q

what impact can low total blood oxygen content have on ventilation

A

low total blood content (anaemia) will have little impact on ventilation if pao2 (o2 in solution in plasma) is normal

204
Q

what effect do all sedetive or anaesthetic drugs have on ventilation

A

will depress ventilation to some degree

205
Q

peripheral and central chemoreceptors responding to h+

A

An increase in co2 increases hydrogen ion concentration in the plasma as well as in the cerebrospinal fluid

central chemoreceptors cannot respond to h+ ions that are not from co2 in the plasma because they cannot cross the blood-brain barrier.

peripheral chemoreceptors will respond to h+ ions whatever source they have originated from

206
Q

the following will be the strongest stimulus to ventilation:

  1. PO2 80mmHg
  2. PCO2 44mmHg
  3. PCO2 38mmHg
  4. Plasma pH7.3
  5. Plasma pH7.6
A

Small increases in PCO2 are all that is required to strongly stimulate ventilation. Large decreases in PO2 are required to do the same thing <60mmHg. Decreases in PCO2 and increases in pH will both slow down ventilation.

207
Q

Which of the following will stimulate ventilation?

  1. Acidosis (pH<7.4)
  2. PCO2 44mmHg
  3. PO2 60mmHg
  4. All of the above will stimulate ventilation
A

All those factors will stimulate ventilation (the fall in PO2 is great enough this time to trigger the peripheral chemoreceptors)

208
Q

What does hypoventilation cause?

A

Hypoventilation means breathing less than normal, i.e. having alveolar ventilation less than the normal value of 4.2L/min. This reduction in breathing means CO2 is retained (not exhaled so readily), and when CO2 levels rise the CO2 is converted into carbonic acid thus raising [H+] and creating acidosis. Exceeding normal alveolar ventilation (4.2L/min) is hyperventilation. Alveolar ventilation could fall below 5L/min (but not below 4.2L/Min) and still be greater than normal.

209
Q

What is the normal ph of extracellular fluid?

A

7.4 ph

210
Q

what happens to which receptors in exercise

A

the body produces lactic acid. the peripheral chemoreceptors will respond to the production of lactic acid in a way central chemoceptors cannot because they cannot cross the blood-brian barrier

211
Q

what will alter ventilation a change in ___ and what pathway will do this

A

changes in plasma ph will alter ventilation via the peripheral chemoreceptor pathway

212
Q

if plasma PH falls___

A

if plasma ph falls, h+ contentration increases and ventilation will be stimulated due to acidosis.

213
Q

if plasma ph rises__

A

plasma ph rises (h+) falls (e.g. vomiting) alkalosis will occur and ventilation will be inhibited.

214
Q

Increased ventilation will drive the equation to the ___

decreased ventilation drives the equation to the __

A

increased ventilation drives the equation to the left (by blowing off co2 and lowers h+)

decreased ventilation drives this equation to the right (by retaining co2 and increasing h+)

215
Q

briefly explain the acid-base balance with respiratory and another system

A

the acid-base balance of the respiratory system, the renal system will work together to try and maintain normal extracellular ph.

if renal has =acid base imbalance, the respiratory will try and compensate to correct it

216
Q

acid-base balance, hypoventilation and hyperventilation

A

hypoventilation causing co2 retention leads to increased h+ and brings about respiratory acidosis

hyperventilation, blowing off more co2 leads to decreased h+ bringing about respiratory alkalosis.

217
Q

if the respiratory system is not the cause of a ph disturbance it is called….

A

metabolic acidosis or metabolic alkalosis - the respiratory system can try and compensate for that and acts to limit damage and reduce the amount of h+ ion concentration.

218
Q

what is normal value of ph

A

7.4

219
Q

useful ph equation

A

ph a hco3/co2

hco3 is controlled by the kidneys

co2 is controlled by the lungs

220
Q

what happens with ventilation during breath holding

A

we will eventually lose consciousness and lose the ability to control ventilation and involuntary start normal ventilation

221
Q

]what happens with ventilation during intended hyperventilation

A

ventilation is reflexible inhibited by an increase in arterial po2 or a decrease in arterial pco2/[h+]

222
Q

respiration and swallowing

A

respiration is inhibited during the swallowing period to avoid aspiration of food or fluid,

swallowing is followed by expiration to dislodge any particles that may be dislodged outwards from the region of the glottis

223
Q

changes in plasma [h+] are detected by __

A

peripheral chemoreceptors

224
Q

increasing [h+] in plasma stimulates

A

ventilation

225
Q

decreasing h+ in plasma ___

A

depresses ventilation

226
Q

PLasma h+ ogten but not always originated from ___

A

co2 so the increase in ventilation helps to bloww off that co2

227
Q

changes in plasma h+

A

will alter ventilation

228
Q

Changes in ventilation will __

A

alter plasma [h+]

229
Q

The respiratory system can therefore be either ____ or ____ for ____

A

the respiratory system can therefore be either the cause of or compensate for acid base disturbences

230
Q

a key equation to remember is ___

A

ph is proportional to bicarbonate divided by co2

ph a hco3/co2

231
Q

our bodies are wholly programmed to ___ when it cannot it causes __

A

our bodies are wholly programmed to get rid of co2, when they cannot it causes immense distress

232
Q

while some ___ is possible, it cannot ___the ___.

A

while some voluntary control is possible, it cannot overrride the chemical control mechanisms.

233
Q

The functional unit of the lung is the pulmonary alveolus.

true or false

A

True. The alveoli are the only point of the respiratory tree where the walls are thin enough to allow gas exchange, and hence they are the only point where functional gas exchange occurs.

The correct answer is ‘True’.

234
Q

Regarding airways and breathing: Vital capacity is the same as Inspiratory Reserve Volume + Functional Residual Capacity.

true or false

A

False. Vital capacity describes the largest volume of air that can voluntarily be exhaled after a maximum inspiration. IRV + FRC misses out tidal volume. Vital capacity can be alternatively described in a number of ways:

  1. Inspiratory Capacity + Functional Residual Capacity
  2. Inspiratory Reserve Volume + Tidal Volume + Functional Residual Capacity
  3. Inspiratory Reserve Volume + Tidal Volume + Expiratory Reserve Volume + Residual Volume

Remember, the term “Capacity” describes where 2 or more “volumes” have been added together.

The correct answer is ‘False’.

235
Q

Alveolar ventilation is defined as the total volume of gas breathed per minute.

true or false

A

false

Alveolar ventilation describes only the volume of gas that reaches the alveoli (and hence is available for gas exchange) per minute. Not all the air we breathe in reaches the alveoli as some gets trapped in dead space and cannot participate in gas exchange.

The correct answer is ‘False’.

236
Q

Regarding airways and breathing: If there are ventilation/perfusion disturbances, the impact is greater on CO2 loss than O2 uptake

true or false

A

False. CO2 is more water-soluble than O2 so can diffuse more readily. For this reason, ventilation/perfusion disturbances often affect CO2 levels less than O2.

The correct answer is ‘False’.

237
Q

Carbon dioxide is carried on the haemoglobin molecule as carboxyhaemoglobin.

Select one:

True

False

A

False. The term “carboxyhaemoglobin” describes carbon monoxide binding to haemoglobin – your carboxyhaemoglobin levels should be neglible!

The correct answer is ‘False’.

238
Q

The volume of blood flowing through the pulmonary circulation per minute is less than in the systemic circulation.

Select one:

True

False

A

False. The two systems are in series with each other so the same volume of blood must flow through each for any given period of time.

The correct answer is ‘False’.

239
Q

The total volume of both lungs is called the vital capacity.

Select one:

True

False

A

False. The total volume of both lungs is Total Lung Volume. Vital capacity describes the maximum volume of air that can be exhaled following a maximum inspiration.

The correct answer is ‘False’.

240
Q

The phrenic nerve takes its origin from the T3, T4 and T5 spinal nerves.

Select one:

True

False

A

False. The phrenic nerve takes it origins from the C4, C4 and C5 spinal nerves

The correct answer is ‘False’.

241
Q

The haemoglobin-O2 saturation curve is moved to the left by a rise in pH.

Select one:

True

False

A

True. Alkalosis increases the affinity of haemoglobin for oxygen and thus shifts the binding curve to the left

The correct answer is ‘True’.

242
Q

Central chemoreceptors respond to changes in H+ concentration.

Select one:

True

False

A

True. Specifically, they respond to changes in H+ concentration in the cerebrospinal fluid (CSF). These H+ are wholly derived from CO2 present in the CSF, which in turn is in equilibrium with CO2 in the plasma so indirectly the central chemoreceptors are responding to increases in CO2 in the plasma. H+ from other metabolic sources cannot cross the blood-brain barrier and so do not stimulate the central chemoreceptors

The correct answer is ‘True’.

243
Q

The term shunt describes the passage of blood through the lungs where the opportunity for gas exchange does not occur.

Select one:

True

False

A

True. Shunt describes the situation where blood is effectively “shunted” from one side of the heart to the other without participating in gas exchange in between. It can happen where part of the lung is not being fully ventilated for some reason e.g. tumour, airway obstruction

The correct answer is ‘True’.

244
Q

The haemoglobin-O2 saturation curve will be shifted downward in an anaemia with normal lung function.

Select one:

True

False

A

False. The oxyhaemglobin binding curve is unaffected in anaemia. In anaemia the amount of oxygen in solution in the plasma is unaffected (providing the lungs are healthy) and therefore the binding of oxygen to red blood cells is normal. The term anaemia describes a fall in the total oxygen content of the blood but remember 98% of the oxygen in the blood is wrapped up in the haemoglobin in red blood cells, it is not in solution in the plasma. If the lungs are working normally, anaemia therefore comes about due to diminished ability of red blood cells as a whole to carry oxygen for one reason or another e.g. lacking in number, or in oxygen binding sites due to iron deficiency. However the red blood cells that are present in the blood are fully saturated at normal PO2, even if they have fewer binding sites than normal.

245
Q

The peripheral chemoreceptors in the carotid bodies are more influenced by arterial PO2 than by arterial oxygen content.

Select one:

True

False

A

True. The peripheral chemoreceptors respond to changes in levels of oxygen in solution (PO2) and not the amount of oxygen wrapped up in hemoglobin (where most of the blood oxygen in found).

246
Q

Peripheral chemoreceptors mediate the hypocapnia (low PCO2) that occurs at high altitude.

Select one:

True

False

A

True. The lower atmospheric PO2 at altitude means arterial PO2 also falls. This is detected by the peripheral chemoreceptors which stimulate ventilation in an attempt to restore normal PO2. The resulting hyperventilation blows of more CO2 than normal leading to hypocapnia.

Medicine 1 (Year 1) (15 decks)

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